My guess is that you have two different problems.

… no 7 chords …

Chord suffixes are document specific (not program specific).

The suffixes need to have play defined.

This is done in the dialog box Chord Suffix Editor. (Click the button Set Play…)

But wait!

Rather than editing the chord suffixes one by one it might be faster to delete all the chord suffixes, and then load a chord suffix library. (File menu > Load Library…)

… doesn't play the bass (Am/G etc.) …

Chord Tool.

Handles appear on all chord symbols.

Context-click the handle on a chord symbol with Alternate Bass (e. g. Am/G).

In the context menu, choose

Edit Chord Definition…

(or work faster: select the chord handle, and hit Return)

You get to the dialog box Chord Definition.

In the pane Play, make sure that Alternate Bass is selected.

Hi Peter and thanks.
But you give me solutions how to go round the problem.
But if I remember correctly Finale v26 did recognize Am/G and the like, and certainly 7 chords.
Can you figure what happened, or am I imagining things?

… if I remember correctly Finale v26 did recognize Am/G and the like, and certainly 7 chords …

I could be wrong, but I think that you remember incorrectly:

The chord symbol playback settings have never been program specific, always document specific.

Does your problem happen in all Finale documents?

However:

You are using Windows Finale - right?

Have you tried with a fresh Preferences file?

Sometimes the culprit can be found in a corrupted Preferences file.